Collect type feedback for fields.

runtime/vm/flow_graph_builder.cc

Index: runtime/vm/flow_graph_builder.cc
diff --git a/runtime/vm/flow_graph_builder.cc b/runtime/vm/flow_graph_builder.cc
index 722118679d35815d476a1d829997d076067ae833..7a87922f03a16a4ddce767ee728678a3379afc80 100644
--- a/runtime/vm/flow_graph_builder.cc
+++ b/runtime/vm/flow_graph_builder.cc
@@ -2595,8 +2595,20 @@ void EffectGraphVisitor::VisitStoreInstanceFieldNode(
                                        type,
                                        dst_name);
   }
-  StoreInstanceFieldInstr* store = new StoreInstanceFieldInstr(
-      node->field(), for_instance.value(), store_value, kEmitStoreBarrier);
+
+  store_value = Bind(BuildStoreExprTemp(store_value));
+  GuardFieldInstr* guard =
+      new GuardFieldInstr(store_value,
+                          node->field(),
+                          Isolate::Current()->GetNextDeoptId());
+  AddInstruction(guard);
+
+  store_value = Bind(BuildLoadExprTemp());
+  StoreInstanceFieldInstr* store =
+      new StoreInstanceFieldInstr(node->field(),
+                                  for_instance.value(),
+                                  store_value,
+                                  kEmitStoreBarrier);
   ReturnDefinition(store);
 }